My wife's 10 year tourist visa expires in late April 2011 and we were thinking of traveling in October 2010. Does the wife need to have more than 6 months left on her visa when we arrive? Is it 6 months (calendar 6 months) or 180 days, or are 6 months not needed?

What is the earliest time to reapply for a new 10 year visa? Does the old one need to expire first, or is there some sort of advance date when a new visa can be applied for?

The visa is valid (allows entry) until expired. The six months applies to passport validity. So if he passport is valid for six months beyond her stay she should be fine.

Thanks Lopburi, that makes more sense than my scenario and it works the same way here in Thailand on the O visa.